Active hospital joiner available (2,4)
I believe the answer is:
on hand
'available' is the definition.
(similar in meaning)
'active hospital joiner' is the wordplay.
'active' becomes 'on' (I've seen this in other clues).
'hospital' becomes 'h'.
'joiner' becomes 'and' (I've seen this before).
'on'+'h'+'and'='ON HAND'
(Other definitions for on hand that I've seen before include "Present or easily available" , "Available like wedding ring?" , "Where digital process is" , "Wedding ring is normally" , "just round the corner" .)