DA then re-engineered fan (8)
I believe the answer is:
adherent
'fan' is the definition.
(I've seen this before)
'da then re-engineered' is the wordplay.
'engineered' is an anagram indicator (I've seen 'engineer' mean this).
'da'+'then'+'re'='dathenre'
'dathenre' with letters rearranged gives 'ADHERENT'.
(Other definitions for adherent that I've seen before include "Person supporting" , "Devotee" , "Supporter, fan" , "Dedicated supporter" , "Staunch follower" .)