Appreciated it’s hot inside military vehicles (6)
I believe the answer is:
thanks
'appreciated it's' is the definition.
I can't judge whether this defines the answer.
'hot inside military vehicles' is the wordplay.
'hot' becomes 'h' (abbreviation eg on taps).
'inside' means one lot of letters goes inside another.
'military vehicles' becomes 'tanks' (tank is a kind of military vehicle).
'h' placed inside 'tanks' is 'THANKS'.
Can you help me to learn more?
(Other definitions for thanks that I've seen before include "recognition?" , "I am grateful" , "Word of gratitude" , "Expressions of gratitude" , "Brief expression of appreciation" .)