A few crossing source of meandering river in France (5)
I believe the answer is:
somme
'river in france' is the definition.
(I've seen this in another clue)
'a few crossing source of meandering' is the wordplay.
'a few' becomes 'some' (both can mean a small amount of something).
'crossing' indicates putting letters inside (to cross can mean to go over or around).
'source of' says to take the initial letters (the start - or source - of the word).
The initial letter of 'meandering' is 'm'.
'some' enclosing 'm' is 'SOMME'.
(Other definitions for somme that I've seen before include "Scene of WW One battles" , "French river known from World War 1" , "WWI battle site" , "First World War battlefield" , "1916 battleground" .)