Drop Ant's partner and run? No trouble (8)
I believe the answer is:
decrease
'drop' is the definition.
(thesaurus)
'ant's partner and run? no trouble' is the wordplay.
'ant's partner' becomes 'dec' (I've seen this before).
'and' says to put letters next to each other.
'run?' becomes 'r' (cricket abbreviation).
'no trouble' becomes 'ease' (I've seen this before).
'dec'+'r'+'ease'='DECREASE'
(Other definitions for decrease that I've seen before include "Dock" , "Reduce in size" , "Make smaller or fewer" , "Iron out the wrinkles" , "Become smaller or fewer" .)