Running late, trains can pose a problem? (10)
I believe the answer is:
tantaliser
'can pose a problem?' is the definition.
(something tantalising might cause a problem)
'running late trains' is the wordplay.
'running' is an anagram indicator.
'late'+'trains'='latetrains'
'latetrains' with letters rearranged gives 'TANTALISER'.
(Other definitions for tantaliser that I've seen before include "Tormentor" , "that's frustrating" , "Cause of frustration" .)