In Paris, bed group of soldiers in unit (5)
I believe the answer is:
litre
'unit' is the definition.
(litre is a kind of unit)
'in paris bed group of soldiers' is the wordplay.
I cannot quite see how this works, but
'soldiers' could be 're' (Royal Engineers) and 're' is present in the answer.
The remaining letters 'lit' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
'in' is the link.
Can you help me to learn more?
(Other definitions for litre that I've seen before include "It's equal to about 1.75 pints" , "non-imperial measure" , "A pint or two" , "Metric liquid measure" , "One thousand cc" .)