Aide could provide estimate (5,4)

'estimate' is the definition.
(a rough idea is an estimate or approximation)

'aide could' is the wordplay.
I cannot really understand how this works, but
an anagram of 'aide' is 'idea' which is present in the answer.
The remaining letters 'rough' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...

'provide' acts as a link.