Scotch broth pulse (5)
I believe the answer is:
throb
'pulse' is the definition.
(throb is a kind of pulse)
'scotch broth' is the wordplay.
'scotch' indicates anagramming the letters (I've seen this in other clues).
'broth' anagrammed gives 'THROB'.
(Other definitions for throb that I've seen before include "Pulsate; regular beat" , "Strong rhythmic beat" , "Pound" , "One's heart may do it" , "Pulse" .)