Regarding organ in school study (8)
I believe the answer is:
research
'study' is the definition.
(thesaurus)
'regarding organ in school' is the wordplay.
'regarding' becomes 're'.
'organ' becomes 'ear' (ear is a kind of organ).
'in' indicates putting letters inside.
'school' becomes 'sch'.
'ear' inserted within 'sch' is 'search'.
're'+'search'='RESEARCH'
(Other definitions for research that I've seen before include "Fact-finding" , "Scientific investigation" , "Scientific study" , "Investigate through study" , "university job" .)