Nothing seen in Manila (3)
I believe the answer is:
nil
'nothing' is the definition.
(eg nil is zero in football)
'in manila' is the wordplay.
'in' says the answer is hidden in the clue.
'NIL' is hidden in the letters of 'manila'.
'seen' is the link.
(Other definitions for nil that I've seen before include "Score of nought" , "Latin zero" , "Nothing, no value" , "Nothing found in senility" , "Nothing, zilch" .)