Somewhat regressive carry on, naturally, will irritate them (5)
I believe the answer is:
annoy
'irritate them' is the definition.
I can't tell whether this defines the answer.
'somewhat regressive carry on naturally' is the wordplay.
'regressive' is a reversal indicator (to regress is to go backwards).
'somewhat' indicates a hidden word.
'yonna' is hidden in the letters of 'carry on naturally'.
'yonna' in reverse letter order is 'ANNOY'.
'will' is the link.
Can you help me to learn more?
(Other definitions for annoy that I've seen before include "Upset" , "be a nuisance" , "Gall" , "Exasperate" , "Irritate, needle" .)