Sob from Serbo-Croat working in nuclear installation (7)
I believe the answer is:
reactor
'nuclear installation' is the definition.
(I've seen this before)
'sob from serbo-croat working' is the wordplay.
'from' indicates named letters should be taken away.
'working' indicates an anagram.
'serbo'+'croat'='serbocroat'
'serbocroat' with 'sob' taken out is 'ercroat'.
'ercroat' is an anagram of 'REACTOR'.
'in' is the link.
(Other definitions for reactor that I've seen before include "Atomic pile" , "(Nuclear) powerplant" , "Device to produce energy by nuclear fission" , "See 3 Down" , "Nuclear power station core" .)