Wise men given no time to join those waiting to see old French fortifications (7,4)
I believe the answer is:
maginot line
'old french fortifications' is the definition.
(20th-century set of French fortifications)
'wise men given no time to join those waiting' is the wordplay.
'wise men' becomes 'magi' (the three wise men from the nativity).
'given' is a charade indicator (letters next to each other).
'time' becomes 't' (abbreviation).
'to join' is a charade indicator (letters next to each other).
'those waiting' becomes 'line' (people waiting in line).
'magi'+'no'+'t'+'line'='MAGINOT LINE'
'to see' acts as a link.
(Other definitions for maginot line that I've seen before include "defensive formation" , "defence of France" , "WW2 French defence against the Germans" , "Pre-WW2 French fortification" .)