Admitting ebbing zest, extremely sloppy leader is one keen to retire? (10)
I believe the answer is:
sleepyhead
'one keen to retire?' is the definition.
(retire can mean to go to bed)
'admitting ebbing zest extremely sloppy leader' is the wordplay.
I cannot really understand how this works, but
'leader' could be 'head' (head is a kind of leader) and 'head' is located in the answer.
The remaining letters 'sleepy' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
'is' is the link.
(Other definitions for sleepyhead that I've seen before include "One dropping off" , "Lazy or inattentive person" , "dozy kid?" , "One may lie in" , "Person given to napping" .)