Fulfilment I found in working for unit (8)
I believe the answer is:
fruition
'fulfilment' is the definition.
The answer and definition can be both acts as well as being singular nouns.
Maybe you can see an association between them that I can't see?
'i found in working for unit' is the wordplay.
'found in' is an insertion indicator.
'working' is an anagram indicator.
'for'+'unit'='forunit'
'forunit' with letters rearranged gives 'frution'.
'i' going inside 'frution' is 'FRUITION'.
Can you help me to learn more?
(Another definition for fruition that I've seen is " Realisation, fulfilment".)