It has no big clientele (6)
I believe the answer is:
creche
'no big clientele' is the definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.
'it' is the wordplay.
I cannot quite understand how this works, but
'it' could be 'e' ('e' can mean 'electronic' which is similar to 'IT') and 'e' is found in the answer.
The remaining letters 'crche' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
'has' acts as a link.
Can you help me to learn more?
(Other definitions for creche that I've seen before include "A day nursery used by working parents" , "Place where infants are cared for" , "Tableau of the Nativity" , "A day care baby-minding business" , "A day nursery for child-minding" .)