War god placed towards the top part of Roman decoration (7)
I believe the answer is:
tessera
'part of roman decoration' is the definition.
'tessera' can be an answer for 'part' (I have seen 'Part of mosaic' mean 'tessera' so perhaps 'part' could also mean 'tessera'). I'm unsure of the 'of roman decoration' bit.
'war god placed towards the top' is the wordplay.
I cannot really see how this works, but
'god' could be 'ra' (Egyptian god) and 'ra' is located in the answer.
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is found within the answer.
The remaining letters 'esse' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for tessera that I've seen before include "Mosaic component" , "Mosaic stone" , "Piece of picture" , "Small stone for mosaics" , "password" .)