Sudden urge I am going to beat (7)
I believe the answer is:
impulse
'sudden urge' is the definition.
(I've seen this before)
'i am going to beat' is the wordplay.
'i am' becomes 'I'm' (contraction).
'going to' says to put letters next to each other.
'beat' becomes 'pulse' (synonyms).
'im'+'pulse'='IMPULSE'
(Other definitions for impulse that I've seen before include "Sudden or instinctive desire" , "Sudden urge to do something" , "Whim; thrust" , "I may cause desire" , "Impel us with sudden urge" .)