Commercial jingle in rhyme is preventing success (7)
I believe the answer is:
adverse
'preventing success' is the definition.
I can't tell whether this definition defines the answer.
'commercial jingle in rhyme' is the wordplay.
I cannot quite see how this works, but
'commercial' could be 'ad' (abbreviation for advertisement) and 'ad' is present in the answer.
'rhyme' could be 'verse' (synonyms) and 'verse' is located in the answer.
No letters remain.
This explanation may well be incorrect...
'is' acts as a link.
Can you help me to learn more?
(Other definitions for adverse that I've seen before include "Dire" , "Inimical" , "Inopportune" , "'Unfavourable, contrary (7)'" , "Contrary -- inauspicious" .)