Force a beat to relax (5)
I believe the answer is:
abate
'relax' is the definition.
(I've seen this before)
'force a beat' is the wordplay.
'force' is an anagram indicator (letters must be forced into a new order).
'a'+'beat'='abeat'
'abeat' with letters rearranged gives 'ABATE'.
'to' is the link.
(Other definitions for abate that I've seen before include "Moderate" , "Go down like storm" , "Wane" , "Relax" , "Die down, slacken off" .)