Poet in squalor, number coming up (5)
I believe the answer is:
munro
'poet' is the definition.
'in squalor number coming up' is the wordplay.
'in' indicates a hidden word.
'coming up' says the letters should be written in reverse.
'ornum' can be found hidden inside 'squalor number'.
'ornum' reversed gives 'MUNRO'.
(Other definitions for munro that I've seen before include "Big Ben" , "Mountain of 3,000 ft or more in Scotland" , "Scottish mountain over three-thousand feet" , "High Scottish mountain" , "Cataloguer of Scottish mountains" .)