Lads drunk outside clubs causing injury (5)
I believe the answer is:
scald
'injury' is the definition.
(I know that scald is a type of burn)
'lads drunk outside clubs' is the wordplay.
'drunk' indicates anagramming the letters.
'outside' means one lot of letters goes inside another.
'clubs' becomes 'c' (abbreviation used in card games such as bridge).
'lads' is an anagram of 'sald'.
'sald' placed around 'c' is 'SCALD'.
'causing' is the link.
(Other definitions for scald that I've seen before include "Burn with hot liquid" , "Burn with water" , "Injure with steam" , "Heat (milk) to near boiling point" , "Injure with hot liquid" .)