The most common and most likely answer to this crossword clue is the 6 letter word ENTAIL
I've seen this crossword clue in The Guardian
E
N
T
A
I
L
More clues leading to the result ENTAIL
- Occasion to be poorly attended by specialist medical department
- Need to take sick to one part of hospital
- Call for nurse before onset of tummy trouble
- Require leads to be taken from excited, naughty dog
- Occasion entrants need to attend in Lycra tops
- Require time during unusual dissection of alienĀ
- Require English with translation of Latin
- Need one in charge when head is sacked
- Involve last of fruit in a line, stewed
- Involve volunteers in line-up
Buddy explains!

The straight part
We know that "Involve" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case involve = entail.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does ENTAIL mean?
ENTAIL verb- To imply or require.
- To settle or fix inalienably on a person or thing, or on a person and his descendants or a certain line of descendants; -- said especially of an estate; to bestow as a heritage.
- To appoint hereditary possessor.
- To cut or carve in an ornamental way.
- That which is entailed. Hence:
- Delicately carved ornamental work; intaglio.