Structure seen in searching (4)
I believe the answer is:
arch
'structure' is the definition.
(arch is a kind of structure)
'in searching' is the wordplay.
'in' indicates the answer is hidden within the clue.
'ARCH' is hidden within 'searching'.
'seen' acts as a link.
(Other definitions for arch that I've seen before include "Main" , "Annoyingly playful" , "Wellington's, perhaps" , "Instep of foot" , "Roguish - superior" .)