Unruly girl was first to be questioned (7)
I believe the answer is:
grilled
'questioned' is the definition.
Both the answer and definition are adjectives. Perhaps you can see a link between them that I can't see?
'unruly girl was first' is the wordplay.
'unruly' indicates anagramming the letters.
'was first' becomes 'led' (to lead is to go first).
'girl' is an anagram of 'gril'.
'gril'+'led'='GRILLED'
'to be' is the link.
Can you help me to learn more?
(Other definitions for grilled that I've seen before include "Cooked under a flame" , "Cooked; interrogated" , "Cooked under flames" , "Cooked by radiant heat" , "Cooked - cross-examined" .)