Capital equipment beginning to appreciate (4)
I believe the answer is:
riga
'capital' is the definition.
(Riga is an example)
'equipment beginning to appreciate' is the wordplay.
'equipment' becomes 'rig' (rig is a kind of equipment**).
'beginning to' suggests taking the first letters.
The first letter of 'appreciate' is 'a'.
'rig'+'a'='RIGA'
(Other definitions for riga that I've seen before include "Capital city of Latvia" , "Baltic port" , "European capital" , "Latvian port" , "capital in Europe" .)