The phrase "able to exert a" is correct and usable in written English.
It can be used when describing someone's capacity or capability to influence or apply force in a particular context.
Example: "The new policy is designed to ensure that the organization is able to exert a positive impact on the community."
Alternatives: "capable of applying a" or "able to apply a".
No one was able to exert a grip.
"They are able to exert a lot of pressure," Ms. Nestle said.
By accepting his offer, Labor may be able to exert a moderating influence.
The Clinton administration, in its waning months, will be less able to exert a calming influence, let alone nudge negotiators toward painful compromises.
A combined Comcast-NBC Universal would be able to exert a good deal of control over old media's internet dreams, to say the least.
That the current President is more personally affable than politically savvy has never been much in doubt, and as a civilian he might prove able to exert a disarming appeal, especially if given the soft soap by satirists.
Shatz suggested that drugs that block beta-amyloid's binding to PirB on nerve-cell surfaces — for example, soluble PirB fragments containing portions of the molecule that could act as decoy — might be able to exert a therapeutic effect.
But mice and people are rather distant cousins — their last common ancestor lived some 70 million years ago — and the human version of FOXP2 evidently was not able to exert a transformative effect on the mouse.
More interesting possibilities had to await the testing of materials that could slow light much more, and therefore were able to exert a stronger pull when they were moving.
Because Mr Meshaal is the conduit for much of Hamas's finances, he is able to exert a major influence on the armed wing of the group, which diverged from the political wing led by Ismail Haniyeh, the Palestinian prime minister.
Additionally, the investigation of the thermo- and photo-oxidation processes reveals that the hybrids nanoparticles are able to exert a remarkable stabilizing action, due to strong physical interaction between Q and CNTs.
