Promo they upset intermittently (4)
I believe the answer is:
hype
'promo' is the definition.
(hype can mean promotion or publicity)
'they upset intermittently' is the wordplay.
'intermittently' means one should take alternating letters.
'they'+'upset'='theyupset'
The alternate letters of 'theyupset' are 'HYPE'.
(Other definitions for hype that I've seen before include "Build up" , "Plug" , "Promotional publicity" , "Blatant or sensational promotion" , "Slang for extravagant promotion of a product" .)