Well-liked surgery, regularly full, in standard environment (7)
I believe the answer is:
popular
'well-liked' is the definition.
(similar in meaning)
'surgery regularly full in standard environment' is the wordplay.
'surgery' becomes 'op' (short for operation).
'regularly' means one should take alternating letters (regularly take one letter, leave next etc.).
'in' is an insertion indicator.
'standard environment' becomes 'par' (I can't justify this - if you can you should believe this answer much more).
The alternate letters of 'full' are 'ul'.
'op'+'ul'='opul'
'opul' going within 'par' is 'POPULAR'.
Can you help me to learn more?
(Other definitions for popular that I've seen before include "In general favour" , "Widely admired" , "Well liked, generally admired" , "Demotic" , "having many fans" .)