Pall, become tiresome (4)
I believe the answer is:
cloy
I believe this is a double definition.
'pall' is the first definition.
(I know that pall can be written as cloy)
'become tiresome' is the second definition.
(I've seen this in another clue)
(Other definitions for cloy that I've seen before include "Sicken with excessive sweetness/richness" , "Make weary through over-sentimentality" , "Cause distaste by excessive sweetness" , "Satiate to the point of disgust" , "Sicken with sentiment" .)