What does the cryptic crossword clue "'Isms' tend somehow to determine outlooks (8)" mean?

The definition is "outlooks". The wordplay uses an anagram. anagram of 'ISMS' + TEND = MINDSETS; definition: "outlooks" The answer is MINDSETS.

'Isms' tend somehow to determine outlooks (8)

Guardian Cryptic #29102 | 5 Across | 2023-06-21 flower