Prudent to claim foul after drop (10)
I believe the answer is:
diplomatic
'prudent' is the definition.
(thesaurus)
'to claim foul after drop' is the wordplay.
'foul' indicates anagramming the letters.
'after' means one lot of letters go next to another.
'drop' becomes 'dip' (I've seen this before**).
'to'+'claim'='toclaim'
'toclaim' anagrammed gives 'lomatic'.
'lomatic' after 'dip' is 'DIPLOMATIC'.
(Other definitions for diplomatic that I've seen before include "Discreet" , "Tactful" .)