Holding head in irritation, I snore unfortunately louder (7)
I believe the answer is:
Here is my best explanation:
'louder' is the definition.
('noisy' is associated in meaning with 'loud')
'holding head in irritation i snore unfortunately' is the subsidiary indication.
'holding' is an insertion indicator.
'head in' indicates taking the first letters.
'unfortunately' is an anagram indicator.
The initial letter of 'irritation' is 'i'.
'isnore' is an anagram of 'noiser'.
'i' put inside 'noiser' is 'noisier'.
(Other definitions for noisier that I've seen before include "Louder", "More loud", "More rowdy", "Less quiet" and "More of a racket".)