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 wordplay.
'holding' means one lot of letters goes inside another.
'head in' suggests taking the first letters.
'unfortunately' indicates an anagram.
The initial letter of 'irritation' is 'i'.
'isnore' is an anagram of 'noiser'.
'i' inserted within 'noiser' is 'NOISIER'.
(Other definitions for noisier that I've seen before include "More of a racket", "Louder", "More loud", "more deafening!", "louder?", "Perhaps more disturbing", "Less quiet" and "More rowdy".)