Leaving the tailor's in better health (9)
I believe the answer is:
outfitter
'better health' is the definition.
The definition and answer can be both people as well as being singular nouns.
Perhaps there's a link between them I don't understand?
'leaving the tailor's in' is the wordplay.
'leaving' becomes 'outer' (I am not sure about this - if you are sure you should believe this answer much more).
'the' becomes 't' (the is pronounced as a 't' sound in some dialects).
'tailor' becomes 'fit' (I've seen this in another clue).
'in' indicates putting letters inside.
't'+'fit'='tfit'
'outer' going around 'tfit' is 'OUTFITTER'.
Can you help me to learn more?
(Other definitions for outfitter that I've seen before include "Supplier" , "who could help in gear selection?" , "One supplies gear" , "Seller of men's clothing" , "Men's clothing shop" .)