Suspect Yard follows in Fife at intervals (4)
I believe the answer is:
iffy
'suspect' is the definition.
(both can mean dubious)
'yard follows in fife at intervals' is the wordplay.
'yard' becomes 'y' (abbreviation).
'follows' says to put letters next to each other.
'at intervals' means one should take alternating letters (letters are taken at regular intervals).
'in'+'fife'='infife'
The alternating letters of 'infife' are 'iff'.
'y' after 'iff' is 'IFFY'.
(Other definitions for iffy that I've seen before include "Full of uncertainty" , "Colloquially uncertain or doubtful" , "Not to be trusted" , "Chancy, suspect" , "Problematic" .)