Visitors speculate about time (6)
I believe the answer is:
guests
'visitors' is the definition.
(guest is a kind of visitor)
'speculate about time' is the wordplay.
I cannot quite understand how this works, but
'time' could be 'est' (EST is an example) and 'est' is present in the answer.
The remaining letters 'gus' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for guests that I've seen before include "Hosts entertain them" , "They are associated with visiting" , "Folk receiving hospitality" , "Company" , "House or hotel visitors" .)