Use up patience, initially, during broadcast (5)
I believe the answer is:
spend
'use up' is the definition.
(synonyms)
'patience initially during broadcast' is the wordplay.
'initially' indicates taking the first letters.
'during' indicates putting letters inside.
'broadcast' becomes 'send' (synonyms).
The initial letter of 'patience' is 'p'.
'p' inserted into 'send' is 'SPEND'.
(Other definitions for spend that I've seen before include "While away" , "Pay out or use up" , "amount" , "Use (money etc)" , "Run through" .)