The most common and most likely answer to this crossword clue is the 4 letter word FULL
I've seen this crossword clue in The Daily Telegraph
F
U
L
L
More clues leading to the result FULL
- Comprehensive with no spare places?
- Satisfied to clean and beat cloth
- See 1dn.
- & 2 Dot’s loaded, upsetting corporations
- If you refill petrol, ends thus?
- End of tie seen at work every day
- Vigorous and in no need of a transfusion?
- Uncut film as large as life
- All-out sort of effort from top brass, say
- Sort of employee that’s fiddled till – about that get angry, right?
Buddy explains!

The straight part
We know that "Vigorous" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case vigorous = full.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 FULL mean?
FULL adjective- Containing the maximum possible amount that can fit in the space available.
- Complete; with nothing omitted.
- Total, entire.
- Having eaten to satisfaction, having a "full" stomach; replete.
- (with of) Replete, abounding with.
- (of physical features) Plump, round.
- Of a garment, of a size that is ample, wide, or having ample folds or pleats to be comfortable.
- Having depth and body; rich.
- Having the mind filled with ideas; stocked with knowledge; stored with information.
- Having the attention, thoughts, etc., absorbed in any matter, and the feelings more or less excited by it.
- Filled with emotions.
- Impregnated; made pregnant.
- (postnominal) Said of the three cards of the same rank in a full house.
- Drunk, intoxicated.
- Fully; quite; very; thoroughly; completely; exactly; entirely.
- Utmost measure or extent; highest state or degree; the state, position, or moment of fullness; fill.
- (of the moon) The phase of the moon when its entire face is illuminated, full moon.
- (freestyle skiing) An aerialist maneuver consisting of a backflip in conjunction and simultaneous with a complete twist.
- (of the moon) To become full or wholly illuminated.
- To baptise.
- To make cloth denser and firmer by soaking, beating and pressing, to waulk, walk