Ship, with hesitation, has problems (4)
I believe the answer is:
sums
'problems' is the definition.
(arithmetic problems)
'ship with hesitation' is the wordplay.
'ship' becomes 'ss'.
'with' is an insertion indicator.
'hesitation' becomes 'um'.
'ss' enclosing 'um' is 'SUMS'.
'has' is the link.
(Other definitions for sums that I've seen before include "Amounts of money" , "Exercises in arithmetic" , "Quantities obtained by addition" , "Calculations" .)