Two seconds hold acceptable for wrestling (4)
I believe the answer is:
sumo
'for wrestling' is the definition.
(I've seen this before)
'two seconds hold acceptable' is the wordplay.
'two seconds' means two substitutions for 'second'.
'second' becomes 's' (common abbreviation).
'second' becomes 'mo' (both are short periods of time).
'hold' is an insertion indicator.
'acceptable' becomes 'u' (as in U and non-U speech).
's'+'mo'='smo'
'smo' placed around 'u' is 'SUMO'.
(Other definitions for sumo that I've seen before include "Japanese wrestling sport of over-weight men" , "Grappling" , "Jap. wrestling" , "foreign form of fighting" , "one of the martial arts" .)