Nostalgic, in more trouble (5)
I believe the answer is:
retro
'nostalgic' is the definition.
(I've seen this in another clue)
'in more trouble' is the wordplay.
'in' says the answer is hidden in the clue.
'RETRO' is hidden within 'more trouble'.
(Other definitions for retro that I've seen before include "in nostalgic style" , "imitating past fashion" , "Type of rocket; backward-looking" , "recreating the past for effect" , "reminding us of the past" .)