Standing by chap on hospital department (9)
I believe the answer is:
permanent
'standing' is the definition.
(similar in meaning)
'by chap on hospital department' is the wordplay.
'by' becomes 'per'.
'chap' becomes 'Man' (I've seen this before).
'on' means one lot of letters go next to another.
'hospital department' becomes 'ENT'.
'per'+'man'+'ent'='PERMANENT'
(Other definitions for permanent that I've seen before include "indestructible" , "that's not changing" , "Lasting indefinitely" , "full-time" , "Lasting, unchangeable" .)