Form of jazz that obviously had to be a hit (5)
I believe the answer is:
bebop
'form of jazz' is the definition.
(I've seen this in another clue)
'be a hit' is the wordplay.
'a hit' becomes 'bop' (I've seen this before).
'be'+'bop'='BEBOP'
'that obviously had to' is the link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for bebop that I've seen before include "Form of modern jazz from about 1940" , "Jazz style of 40s" , "music played in jazz club" , "1940s' form of modern jazz" , "Fast, complex jazz" .)