Out of breath, dear? Worn out (10)
I believe the answer is:
threadbare
'worn out' is the definition.
(I've seen this before)
'out of breath dear?' is the wordplay.
'out of' is an anagram indicator.
'breath'+'dear'='breathdear'
'breathdear' anagrammed gives 'THREADBARE'.
(Other definitions for threadbare that I've seen before include "Shabby" , "deprived of nap" , "Hackneyed" , "cliche-ridden" , "the worse for wear" .)