Land assistant in the first month (5)
I believe the answer is:
japan
'land' is the definition.
(Japan is an example)
'assistant in the first month' is the wordplay.
'assistant' becomes 'pa' (personal assistant).
'in the' means one lot of letters goes inside another.
'first month' becomes 'jan' (abbreviation for January).
'pa' going into 'jan' is 'JAPAN'.
(Other definitions for japan that I've seen before include "'Country of more than 3,000 islands (5)'" , "Twelve [VARNISH]" , "Glossy coating" , "Far Eastern island country" , "Country in Far East" .)