Bay is no longer easy to see from the heads (5)
I believe the answer is:
inlet
'bay' is the definition.
(I've seen this before)
'no longer easy to see from the heads' is the wordplay.
I cannot really see how this works, but
'no' could be 'n' (common abbreviation) and 'n' is found in the answer.
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is found in the answer.
The remaining letters 'ile' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
'is' acts as a link.
Can you help me to learn more?
(Other definitions for inlet that I've seen before include "Opening through which fluid can pass" , "Strip of water extending from sea into land" , "Sound" , "access point" , "Small bay or creek" .)