Foul made by Rodri in action against Hearts (6)
I believe the answer is:
horrid
'foul' is the definition.
(thesaurus)
'rodri in action against hearts' is the wordplay.
'in action' indicates an anagram (I've seen this in other clues).
'against' says to put letters next to each other.
'hearts' becomes 'h' (abbreviation used in card games e.g. bridge).
'rodri' is an anagram of 'orrid'.
'orrid' put after 'h' is 'HORRID'.
'made by' is the link.
(Other definitions for horrid that I've seen before include "Nasty, frightening" , "Hideous" , "Repulsive" , "Distasteful" , "Frightful" .)