Gently strike a girl – on the knee (7)
I believe the answer is:
patella
'knee' is the definition.
(I've seen this before)
'gently strike a girl aeur on the' is the wordplay.
I cannot quite see how this works, but
'gently' could be 'p' (musical abbreviation for 'piano', softly) and 'p' is located in the answer.
'a' is within the answer.
'girl' could be 'ella' (girl's name) and 'ella' is found in the answer.
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is located in the answer.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for patella that I've seen before include "The formal kneecap" , "Knee bone" , "positioned on each knee" , "A pallet (anag.)" , "showing a bit of leg" .)