Widens to one fifty then enters days of occurrence (7)
I believe the answer is:
dilates
'widens' is the definition.
(dilating is a kind of widening)
'one fifty then enters days of occurrence' is the wordplay.
I cannot really understand how this works, but
'one' could be 'i' (Roman numeral) and 'i' is located in the answer.
'fifty' could be 'l' (Roman numeral) and 'l' is found in the answer.
'days' could be 'dates' (date is a kind of day) and 'dates' is found within the remaining letters.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
'to' is the link.
Can you help me to learn more?
(Other definitions for dilates that I've seen before include "Enlarges" , "Makes larger" , "speaks at length" .)