Perhaps it's a headlock (5)
I believe the answer is:
tress
'a headlock' is the definition.
Although both the answer and definition are singular nouns, I don't see how they can define each other.
'perhaps it's' is the wordplay.
I cannot really see how this works, but
'it's' could be 'es' ('e' can mean 'electronic' which is similar to 'IT') and 'es' is found in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for tress that I've seen before include "Long lock or plait of hair" , "Long piece of hair" , "Obsolete support" , "Braid of hair" , "Rests (anag.)" .)