Restraint shown by group of soldiers crossing river (3-4)
I believe the answer is:
leg-iron
'restraint' is the definition.
(I've seen this before)
'soldiers crossing river' is the wordplay.
'soldiers' becomes 'legion' (I've seen this before).
'crossing' is an insertion indicator (to cross can mean to go over or around).
'river' becomes 'r' (abbreviation).
'legion' going around 'r' is 'LEG-IRON'.
'shown by group of' is the link.
This may not be right. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for leg-iron that I've seen before include "Ankle restraint for a prisoner" , "Fetter" .)