Have in mind to be nasty (4)
I believe the answer is:
mean
I believe this clue is a double definition.
'have in mind' is the first definition.
(synonyms)
'be nasty' is the second definition.
(similar in meaning)
'to' is the link.
(Other definitions for mean that I've seen before include "Type of average" , "Stand for - penny-pinching" , "Average or mingy" , "Import" , "Stingy in average way" .)