Joined in: searched outside (8)
I believe the answer is:
combined
'joined' is the definition.
(I've seen this before)
'in searched outside' is the wordplay.
'searched' becomes 'combed' (combing is a kind of searching).
'outside' indicates putting letters inside.
'in' put inside 'combed' is 'COMBINED'.
(Other definitions for combined that I've seen before include "Merged" , "Joined together" , "joint solution" .)