Long to see husband enrolled in service (4)
I believe the answer is:
ache
'long to' is the definition.
(thesaurus)
'husband enrolled in service' is the wordplay.
I cannot really understand how this works, but
'husband' could be 'h' and 'h' is found in the answer.
'service' could be 'ace' (ace is a kind of service) and 'ace' is present in the remaining letters.
No letters remain.
This may be the basis of clue (or it may be nonsense).
'see' acts as a link.
Can you help me to learn more?
(Other definitions for ache that I've seen before include "Suffer dull pain" , "Persistent dull pain" , "Nagging pain" , "Dull continuous pain" , "Dull prolonged pain" .)