Saint joins sailor in an attempt (4)
I believe the answer is:
stab
'an attempt' is the definition.
(to have a stab is to attempt something)
'saint joins sailor' is the wordplay.
'saint' becomes 'st' (abbreviation).
'joins' means one lot of letters go next to another.
'sailor' becomes 'ab' (abbreviation for able seaman).
'st'+'ab'='STAB'
'in' is the link.
(Other definitions for stab that I've seen before include "Attack with a knife" , "Wound with a dagger" , "Run through - essay" , "Pierce with a dagger" , "pink" .)