Expressions of relief assume a certain magnitude, we hear (5)
I believe the answer is:
sighs
'expressions of relief assume a certain' is the definition.
I can't tell whether this definition defines the answer.
'magnitude we hear' is the wordplay.
'magnitude' becomes 'size' (size is a kind of magnitude).
'we hear' indicates a 'sounds like' (homophone) clue.
'size' sounds like 'SIGHS'.
Can you help me to learn more?
(Other definitions for sighs that I've seen before include "Lamentations" , "Exhales sadly" , "Yearns" , "Sounds of weariness" , "Bridge of - - (Venice)" .)