Keep referring to Territorial Army at home (6)
I believe the answer is:
retain
'keep' is the definition.
(retaining is a kind of keeping)
'referring to territorial army at home' is the wordplay.
'referring to' becomes 're'.
'territorial army' becomes 'ta'.
'at home' becomes 'in' ('in' can be similar in meaning to 'at home').
're'+'ta'+'in'='RETAIN'
(Other definitions for retain that I've seen before include "Keep; remember" , "Save" , "Continue to hold on to" , "Hire - keep" , "Hold onto" .)