Old soldiers pointing to sign (4)
I believe the answer is:
omen
'sign' is the definition.
(omen is a kind of sign)
'old soldiers' is the wordplay.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'soldiers' becomes 'men' (I've seen this before**).
'o'+'men'='OMEN'
'pointing to' is the link.
(Other definitions for omen that I've seen before include "Harbinger, augury" , "Augury, portent" , "Gloomy sign" , "Prophetic significance" , "Augur" .)