Extremely lawful to ask (7)
I believe the answer is:
solicit
'to ask' is the definition.
(I know that solicit is a more specific form of ask)
'extremely lawful' is the wordplay.
'extremely' becomes 'so' ('so' can mean 'extremely' or 'very').
'lawful' becomes 'licit' (synonyms).
'so'+'licit'='SOLICIT'
(Other definitions for solicit that I've seen before include "Drum up business" , "Tout" , "Try to obtain (something) from someone" , "Make request (for business etc)" , "Petition - importune" .)