Capital equipment source of adjustments (4)
I believe the answer is:
riga
'capital' is the definition.
(Riga is an example)
'equipment source of adjustments' is the wordplay.
'equipment' becomes 'rig' (rig is a kind of equipment**).
'source of' indicates taking the first letters.
The initial letter of 'adjustments' is 'a'.
'rig'+'a'='RIGA'
(Other definitions for riga that I've seen before include "Capital city of Latvia" , "European capital" , "Latvian capital" , "Fix a rig up here for the Latvians" , "Baltic port" .)