Spot, we hear, for detailed description (4)
I believe the answer is:
spec
'detailed description' is the definition.
(I've seen this before)
'spot we hear' is the wordplay.
'spot' becomes 'speck' (I've seen this before).
'we hear' indicates a 'sounds like' (homophone) clue.
'speck' sounds like 'SPEC'.
'for' is the link.
(Other definitions for spec that I've seen before include "Gamble (colloq.)" , "Required standard of workmanship" , "Awkward, clumsy" , "Instructions" , "estimation?" .)