Sounds of relief of audible dimensions (5)
I believe the answer is:
sighs
'sounds of relief' is the definition.
(I've seen this in another clue)
'audible dimensions' is the wordplay.
'audible' shows a homophone (sound like).
'dimensions' becomes 'size' (I've seen this before).
'size' sounds like 'SIGHS'.
'of' is the link.
(Other definitions for sighs that I've seen before include "Lamentations" , "Exhales audibly" , "Sounds despondent" , "Exhales sadly" , "Sounds of weariness" .)