Less welcoming here in Calais leading to hesitation (5)
I believe the answer is:
icier
'less welcoming' is the definition.
(to be icy is to behave unwelcomingly)
'here in calais leading to hesitation' is the wordplay.
'here in calais' becomes 'ici' ('here' in French).
'leading to' says to put letters next to each other (some letters go before or lead others).
'hesitation' becomes 'er' (sound used when hesitating).
'ici'+'er'='ICIER'
(Other definitions for icier that I've seen before include "More cold - really freezing" , "increasingly frigid" , "Even more frozen" , "With more hostility" , "with more reserve" .)